JP2003241535A - Belt moving device and image forming apparatus equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain the speed fluctuation of a belt such as bounding and positional deviation from a belt target position, to realize accurate position control, and to prevent the color slurring of a formed image so as to form a high-quality image. <P>SOLUTION: A command 1 on a belt surface target position is directly converted into a driving shaft target position (angle). A command 2 on the belt surface target position is compared with a belt surface position (surface target position) by a comparison means 301, and deviation is arithmetically calculated by a surface position control means 302 and converted into the driving shaft target position (angle) and added to the command 1 by an addition means 303. The deviation between the driving shaft target position (angle) and a driving shaft angle is obtained by the comparison means 304 and arithmetically calculated by a position control means 305, and given to the motor of a driving object as a current, whereby the driving object is driven to follow a target position. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls the movement of a belt, and more specifically, a belt moving device capable of controlling the position of an intermediate transfer belt provided in an image forming apparatus such as a color printer with high accuracy. The present invention relates to an image forming apparatus including the device.

[0002]

2. Description of the Related Art The position of an intermediate transfer belt used in an image forming apparatus such as a color printer is controlled by a belt conveying device. FIG. 18 is a plan view showing a conventional belt conveying device (disclosed in Japanese Patent Laid-Open No. 6-263281). This belt conveyor is an endless belt 180.
Encoder 1803 on the drive roll 1802 for driving 1
Is provided, and the index signal is generated once each time the drive roll 1802 rotates once. Further, a mark 1804 is provided at one place on the belt 1801, and the passage time is read by the sensor 1805.

A control means (not shown) controls the belt 18 based on the relationship between the index signal and the mark detection signal.
The speed fluctuation of 01 (eccentricity of the drive shaft) is obtained, and the speed is controlled so as to correct the eccentricity. The belt 1801 is used as an intermediate transfer belt of the image forming apparatus and rotates for the number of colors used for image formation. The pattern of the driving speed of the first color is read by the mark 1804 on the belt 1801 and the second color is read. The following speed patterns are used.

Further, due to the eccentricity of the drive roll 1802,
In order to prevent the speed fluctuation of the belt 1801 from occurring, the driving roll 1 is set so as to cancel the speed fluctuation of the belt 1801.
802 speed control. Specifically, by utilizing the deviation of the belt circumference, the rotation angle of the drive roll 1802 and the belt 1
The correspondence of the speed fluctuation of 801 is obtained by Fourier transform, and the phase and the amplitude are added to the target speed of the driving roll 1802, and the belt 1
The speed of 801 is controlled to be constant.

[0005]

However, in the conventional belt conveying device, the belt 1801 is controlled by speed control.
Since the position is controlled, the position deviation increases with time. In particular, when four color toners of black, yellow, magenta, and cyan are used by being sequentially superposed on the intermediate transfer belt, as in a color copy, a color shift appears. When the position error is caused by disturbance or the like, the color shift is left as it is. That is, in the case of position control, even if a color shift occurs at a certain point, the target position can be followed thereafter. On the other hand, in the above conventional speed control,
There was a problem that the misaligned state could not be resolved after the position error occurred.

The speed fluctuation control of the drive roll 1802 is effective at a low frequency such as the rotation cycle of the drive roll 1802, but it can cope with speed fluctuation at a high frequency to some extent such as banding. There was a problem that I could not.

In order to solve the above-mentioned problems of the prior art, the present invention can reduce the belt speed fluctuation such as bounding and the position deviation from the belt target position, and can carry out highly accurate position control. An object of the present invention is to provide an image forming apparatus equipped with the apparatus, which can prevent color misregistration of an image to be formed and can form a high quality image.

[0008]

[Means for Solving the Problems]
In order to achieve the object, a belt moving device according to the invention of claim 1 comprises a drive shaft for moving the belt, and a transmission means for transmitting a driving force from a motor to the drive shaft.
In a belt moving device that moves a belt by a driving force from the motor, a marker detecting unit that detects a marker provided on the belt for recognizing a position in the moving direction of the belt, and a rotation state of the drive shaft are detected. Rotation state detecting means for detecting, first correction information creating means for creating correction information for correcting the position in the moving direction of the belt based on the detection result of the marker detecting means, and detection of the rotation state detecting means Based on the result, second correction information creating means for creating correction information for correcting the rotation state of the drive shaft, and moving the motor based on the correction information of the first and second correction information creating means. And a control means for controlling.

According to the first aspect of the present invention, when the belt and the drive shaft slip and the belt deviates from the target position,
By detecting the position of the belt surface, the target position of the rotation angle of the drive shaft can be corrected by the amount of the belt deviation, and the position of the belt surface can be returned to the position when there is no slip. When the belt deviates from the target position due to the eccentricity of the drive shaft, the position of the belt surface is measured, and the target position of the drive shaft rotation angle is corrected by the amount of the belt deviation to adjust the belt surface position to the eccentricity of the drive shaft. It can be returned to its original position. As a result, it becomes possible to suppress the displacement of the belt from the target position.

According to a second aspect of the present invention, in the belt moving apparatus according to the first aspect, the first correction information creating means sets the maximum response frequency of the correction information to be created to the second response information. It is characterized in that it is smaller than the maximum response frequency of the correction information created by the correction information creating means.

According to the second aspect of the invention, the position control of the belt having a low rigidity lowers the response frequency so as not to excite resonance. The drive system from the motor to the drive shaft, which has higher rigidity than the belt, increases the response frequency and performs position control to cancel the eccentric disturbance of each shaft. The deviation of the belt is controlled by the first correcting means, and other disturbances are mainly handled by the second correcting means, so that the deviation from the belt target position can be suppressed.

Further, in the belt moving device according to the invention of claim 3, in the belt moving device for driving the belt by rotating the drive shaft by driving the motor, the detecting means for detecting the surface position of the belt, and the detecting means. And a position control means for feeding back the surface position detected by the means to cause the surface position of the driven object to follow the target position.

According to the invention of claim 3, the resonance frequency of the belt is increased by increasing the rigidity of the belt, and the belt surface position in which the control band is increased is directly feedback-controlled to thereby obtain a position from the belt target position. It becomes possible to suppress the deviation.

In the belt moving device according to the invention of claim 4, in the belt moving device for driving the belt by rotating the drive shaft by driving the motor, a rotation state detecting means for detecting a rotation state of the motor shaft is provided. A control unit that feeds back the rotation state detected by the rotation state detection unit to perform a movement control for causing the motor shaft target position to follow the target position of the motor shaft so as to eliminate the deviation from the target surface position of the belt. It is characterized by having and.

According to the invention of claim 4, since the rotation state of the motor shaft is fed back, a mechanical error such as eccentricity of the transmission system from the motor shaft to the drive shaft position and a transmission system from the drive shaft to the belt surface position. When there is a mechanical error such as eccentricity and the belt and the drive roller slip, when the belt surface position is detected, the motor shaft rotation angle target position is corrected by the belt deviation and the belt surface position is not slipped. By returning to the position of, it is possible to suppress the positional deviation from the belt target position.

A belt moving device according to a fifth aspect of the present invention is the belt moving device according to any one of the first to fourth aspects, wherein a tooth is provided at least at one position in the axial direction of the drive shaft on which the belt is stretched. Is formed, and teeth that mesh with the teeth of the drive shaft are formed on the belt, and the belt is moved by rotation of the drive shaft.

According to the fifth aspect of the present invention, the belt and the drive shaft are meshed with each other by teeth, so that the positional deviation from the target position can be suppressed.

A belt moving device according to a sixth aspect of the present invention is the belt moving device according to any one of the first to fourth aspects, wherein the drive surface of the drive shaft is provided with a member having a large friction coefficient, It is characterized in that the belt is moved by rotation of the drive shaft.

According to the sixth aspect of the present invention, by using the drive shaft having a large friction coefficient, the belt slip can be reduced and the displacement from the target position can be suppressed.

A belt moving device according to a seventh aspect of the present invention is the belt moving device according to any one of the first to sixth aspects, wherein the belt is an intermediate transfer belt and / or a paper provided in an image forming apparatus. It is a conveyor belt.

According to the seventh aspect of the present invention, the belt to be driven is the intermediate transfer belt of the image forming apparatus or the paper conveying belt to prevent misalignment during image formation in the image forming apparatus. Highly accurate image formation can be performed.

Further, in the belt moving device according to the invention of claim 8, in the invention according to any one of claims 1 and 2, the control means includes a controller from a target drive shaft angle with respect to the drive shaft. When the relationship between the crossover frequency Wcd of the open-loop transfer characteristic up to the drive shaft angle and the natural frequency Wpd from the drive shaft torque to the surface position of the belt is Wcd> Wpd, the target drive shaft angle of the belt is set to the target drive shaft angle. It is characterized in that control is performed so that there is no deviation from the target surface position.

According to the invention of claim 8, when the rigidity from the torque generated by the motor to the drive shaft angle is high and the rigidity from the drive shaft torque to the surface position of the belt is low, that is, the motor is driven by the torque generated. When the resonance frequency up to the shaft angle is higher than the drive shaft torque to the surface position of the belt, the crossover frequency Wcd of the open loop transfer characteristics from the target drive shaft angle to the drive shaft angle including the controller can be increased, and the response is stable. It becomes possible to configure a control system with high performance. Further, the deviation from the target surface position of the belt can be eliminated by adding it to the target drive axis angle, so that the positional deviation can be suppressed.

According to a ninth aspect of the present invention, in the belt moving apparatus according to the fourth aspect, the control means includes a mechanical system from a target motor shaft angle with respect to the drive shaft to a controller and the drive shaft. When the relationship between the crossover frequency Wcm of the open-loop transfer characteristics up to the motor shaft angle and the natural frequency Wpd from the drive shaft torque to the surface position of the belt is Wcm> Wpd, the target motor shaft angle is set to the target motor shaft angle. It is characterized in that control is performed so that there is no deviation from the target surface position.

According to the ninth aspect of the invention, when the rigidity from the torque generated by the motor to the motor shaft angle is high and the rigidity from the drive shaft torque to the surface position of the belt is low, that is, the torque generated from the motor is used for driving. When the resonance frequency up to the motor shaft angle including the mechanical system up to the shaft is higher than the drive shaft torque to the belt surface position, the crossover frequency Wcm of the open loop transfer characteristic from the target motor shaft angle up to the motor shaft angle including the controller is increased. Therefore, it becomes possible to construct a stable and responsive control system. Further, the deviation from the target surface position of the belt can be eliminated by adding it to the target motor shaft angle, and the position deviation can be reduced.

Further, in the belt moving device according to the invention of claim 10, in the invention of claim 3, the control means crosses open loop transfer characteristics from a target position to a surface position of the belt including a controller. Frequency Wcs,
When the relationship of the natural frequency Wpdm from the drive shaft torque or the motor shaft torque to the surface position of the belt is Wpdm> Wcs, and stable control is possible, only the surface position of the belt is fed back to target the belt. The feature is that control is performed so that there is no deviation from the surface position.

According to the tenth aspect of the invention, even if the belt has a high rigidity, feedback control of the surface position of the belt can realize control with excellent responsiveness and stability, and the target surface of the belt can be realized. It becomes possible to eliminate the deviation from the position.

Further, the belt moving device according to the invention of claim 11 is the belt moving device according to any one of claims 1, 2 and 8, wherein the control means detects the rotation state detecting means. Intersection of the crossover frequency Wcd of the inner feedback loop that feeds back the rotational state of the drive shaft to follow the drive shaft target position and the open loop transfer characteristic from the target position to the surface position of the belt including the controller of the inner feedback loop. The relationship of the frequency Wcs is characterized in that the control of the outer feedback loop is performed with Wcd> Wcs.

According to the eleventh aspect of the present invention, when the resonance frequency from the drive shaft to the belt surface position is low with respect to the target drive shaft angle, the gain of the outer feedback loop is suppressed and the target drive shaft angle is stably maintained. It can be changed.

The belt moving device according to the invention of claim 12 is the belt moving device according to any one of claims 4 and 9, wherein the control means is the drive shaft detected by the rotation state detecting means. Crossing frequency Wcm of the inner feedback loop that feeds back the rotation state of the motor and follows the drive shaft target position, and crossing frequency Wcs of the open loop transfer characteristic from the target position to the surface position of the belt including the controller of the inner feedback loop. Is to execute control of the outer feedback loop with Wcm> Wcs.

According to the twelfth aspect of the present invention, with respect to the target motor shaft angle, the transmission system from the motor to the drive shaft,
When the resonance frequency of the belt surface position from the drive shaft is low, the gain of the outer feedback loop is suppressed, and the target motor shaft angle can be stably changed.

The belt moving device according to a thirteenth aspect of the present invention is the belt moving device according to any one of the first to fourth aspects of the present invention, wherein the control means adds a disturbance estimation observer to the PI controller. It is characterized in that it has an integration characteristic of -20 db / dec as the inclination of the cross frequency Wcs of the open loop transfer function from the target position to the surface position of the belt.

According to the thirteenth aspect of the present invention, for the minor loop, stable position control is executed by the PI controller, and position fluctuation due to disturbance that cannot be removed by the position control is accurately controlled by the disturbance estimation observer. Therefore, stable position control can be achieved in the entire system by setting the outer feedback loop, that is, the slope of the crossover frequency Wcs of the open loop transfer function from the target position to the surface position of the belt to the integral characteristic of −20 db / dec. Like

A belt moving device according to a fourteenth aspect of the present invention is the belt moving device according to any one of the first to fourth, tenth to thirteenth aspects, wherein the control means is a ramp when driving of the belt is started. The target position of the function is multiplied by a function to make it a comparison signal of the measurement output as a new target position, and the function to smooth the target position is multiplied by the reciprocal of the transfer function of the controlled object It is characterized in that a feedforward system circuit for supplying a feedforward current is provided.

According to the fourteenth aspect of the present invention, since the target position of the ramp function is multiplied at the start of driving the belt, the position control with a small overshoot and vibration can be executed. .

According to a fifteenth aspect of the invention, in the belt moving device according to the fifth aspect, the teeth are
It is characterized in that it is formed on a portion other than the image forming portion on the belt.

According to the fifteenth aspect of the present invention, since the teeth are arranged in the area other than the image forming portion of the belt, vibration due to the teeth is not transmitted to the image forming portion, and banding and displacement can be reduced. .

A belt moving device according to a sixteenth aspect of the present invention is the belt moving device according to any one of the fifth and seventh aspects, wherein the belt is stretched by the drive shaft and a plurality of rollers. At least the transfer nip roller among the plurality of rollers has an axial length that does not contact the teeth of the belt.

According to the sixteenth aspect of the present invention, since the teeth do not come into contact with the transfer nip portion of the belt, vibrations due to the teeth are not transmitted to the image forming portion, so that banding and displacement can be reduced. Become.

A belt moving device according to a seventeenth aspect of the present invention is the belt moving device according to any one of the first to sixteenth aspects, wherein the transmission means from the motor to the drive shaft is a timing belt and a timing pulley. It is characterized by being composed of.

According to the seventeenth aspect of the present invention, since the transmission means is composed of the timing belt and the timing pulley, the belt is less likely to be displaced with respect to the drive shaft, and the noise is smaller than that of the gear drive, and direct drive is possible. Power consumption can be reduced compared to.

The belt moving device according to the invention of claim 18 is the belt moving device according to any one of claims 1 to 16, wherein the transmission means from the motor to the drive shaft is a gear. It is characterized by

According to the eighteenth aspect of the invention, since the transmission means is constituted by the gear, the belt is less likely to be displaced with respect to the drive shaft, and the rigidity can be increased as compared with the drive of the timing belt and the timing pulley. , It becomes possible to reduce the power consumption as compared with the direct drive.

A belt moving device according to a nineteenth aspect of the present invention is the belt moving device according to any one of the first to sixteenth aspects, wherein the transmission means from the motor shaft to the drive shaft is a motor shaft and a drive shaft. It is characterized in that the shaft is integrated or is a direct drive in which the motor shaft and the drive shaft are fastened by a coupling.

According to the nineteenth aspect of the present invention, since the belt is directly driven by directly connecting the motor shaft, the belt is not displaced with respect to the drive shaft, and the transmission system by the timing belt and the timing pulley and the transmission by the gear are performed. Compared to the system, the noise is low and the rigidity can be increased.

Further, in the belt moving device according to the invention of claim 20, in the invention according to any one of claims 1 to 19, the control means comprises a slit pattern detected by the marker detection means. It is characterized by comprising signal interpolation means for A / D converting the marker and performing position interpolation between the slit patterns indicated by the detected marker based on the output of the A / D conversion.

According to the twentieth aspect of the invention, even if an inexpensive marker detection means having a wide slit pattern is used, the analog output by the detection of the slit is A / D.
By converting and interpolating between the slits, high resolution can be achieved and highly accurate position control can be performed.

Further, in the belt moving device according to the invention of claim 21, in the invention according to any one of claims 1 to 20, the control means comprises a slit pattern detected by the marker detecting means. It is characterized by comprising a signal interpolating means for temporally interpolating between the pulse edges of the marker signal pulse with a constant interval clock having a shorter cycle than the signal pulse.

According to the twenty-first aspect of the present invention, even when the marker detecting means is inexpensive and has a wide slit pattern, a constant interval clock having a period shorter than the signal pulse between the pulse edges for detecting the slits. By temporally interpolating, the resolution can be increased and the position control can be performed with high accuracy.

The belt moving device according to the invention of claim 22 is the belt moving device according to any one of claims 1 to 21, wherein the control means is a single DSP or a single microcomputer. It is characterized in that the belt is used to drive and control the belt.

According to the invention of claim 22, since the software servo is executed by the single DSP or the single CPU, the calculation of the controller and the observer, the target value locus, and the feedforward calculation can be processed by the software. Therefore, it is possible to perform highly accurate positioning control at low cost without requiring a complicated circuit.

Further, in the belt moving device according to the invention of claim 23, in the invention according to claim 22, the control means performs control calculation for servo drive calculation using the DSP or the microcomputer. It is characterized in that a calculation result discretized with a sampling time is given as an input to the motor.

According to the twenty-third aspect of the present invention, since the software servo is used and the PI controller, the disturbance estimation observer, the new target position, and the feedforward value are discretized and calculated in the sampling time, highly accurate positioning control is performed. Can be done.

A belt moving device according to a twenty-fourth aspect of the present invention is the belt moving device according to any one of the first to twenty-third aspects, wherein the rotation state detecting means is the drive shaft or the motor shaft. It is an eccentricity correction encoder provided coaxially.

According to the twenty-fourth aspect of the present invention, even if eccentricity occurs in the encoder attached to the drive shaft or the motor shaft, the eccentricity can be corrected, so that the eccentric position error does not occur and the position control of the drive shaft and the motor shaft is improved. You can do it with precision.

An image forming apparatus according to a twenty-fifth aspect of the present invention is an image forming apparatus equipped with the belt moving device according to any one of the first to twenty-fourth aspects, which is for forming the belt image. And an image forming means for forming a color image of a plurality of colors on a transfer paper by controlling the movement of the intermediate transfer belt.

According to the twenty-fifth aspect of the present invention, since the movement control of the intermediate transfer belt can be performed with high accuracy, color misregistration of the color image on the transfer paper can be prevented and a high quality image can be formed. become.

[0058]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a belt moving device according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a perspective view showing the overall configuration of a belt moving device according to the present invention. Hereinafter, a configuration example of controlling the movement of the intermediate transfer belt for image transfer of the image forming apparatus will be described.

The intermediate transfer belt 101 to be driven is
A belt drive motor 106, which is a drive source, is connected and driven via a drive shaft 102, a drive shaft timing pulley 103, and a timing belt 104. On the surface of the intermediate transfer belt 101, an encoder scale 107 is formed outside the image area in a slit shape having a predetermined length along the transport direction. An optical head (sensor) 108 is arranged so as to face the encoder scale 107 of the intermediate transfer belt 101, and detects the movement of the encoder scale 107. The drive shaft 102 is provided with a drive shaft encoder 109 that detects the rotation of the drive shaft 102.

The photoconductor 110 includes a drive shaft 111, a drive shaft timing pulley (not shown), and the timing belt 1.
The drum driving motor 113 is connected via 12 and is driven. The drive shaft 111 of the photoconductor 110 is provided with a rotary encoder 114 for detecting rotation. Also,
Similarly, the paper transfer roller 115 is also connected to and driven by a motor (not shown) that is a drive source via a transmission system such as a timing pulley and a timing belt.

Seen in the moving direction of the intermediate transfer belt 101,
The photoconductor 1 is provided on the front side in the moving direction with the laser head 116 interposed therebetween.
10 is arranged, and the paper transfer roller 115 is arranged on the moving direction side. The photoreceptor 110 directly contacts the intermediate transfer belt 101 and rotates. Further, the intermediate transfer belt 101 and the paper transfer roller 115 are in contact with each other via the printing paper and rotate. A charging roller and a cleaning blade (not shown) are arranged adjacent to the intermediate transfer belt 101 and the photoconductor 110.

In the above description, the intermediate transfer belt 101 is used as the drive target, but the same transmission mechanism is used when the paper transport belt is constructed. Although the above-mentioned transmission mechanism is configured to use a timing belt, it may be a transmission mechanism using gears or gears, or a direct mechanism in which a motor is directly connected to a drive target. In addition, a direct drive configuration in which the motor shaft of the belt drive motor 106 and the drive shaft 102 are fastened with a coupling may be used. Further, although the mounting location of the encoder is the drive shaft to be driven, it may be directly connected to the motor shaft.

An eccentricity correction encoder can be used as the drive shaft encoder 109 attached to the drive shaft 102 of the intermediate transfer belt 101 or the rotary encoder 114 attached to the drive shaft 111 of the photoconductor 110. In this case, it is possible to correct even if the encoder has eccentricity, and it is possible to prevent the occurrence of an eccentric position error during position control of the motor.

FIG. 2 is a block diagram (hardware configuration diagram) showing a drive system of the moving mechanism of the intermediate transfer belt 101.
Is. The microcomputer 201 is in charge of controlling the entire moving mechanism. A microprocessor (CPU) 202, a read only memory (ROM) 203, and a random access memory (RAM) 204 are connected to the microcomputer 201 via buses.

The intermediate transfer belt 101 described above is also used.
The sensor output from the optical head 108 and the drive axis encoder 109 of the
F) 205 and input to the microcomputer 201 via the bus 206. Similarly, regarding the sensor output from the drum drive shaft encoder (rotary encoder) 114 of the photoconductor 110, the state detection I / F 207 and the bus 20 are also provided.
It is input to the microcomputer 201 via 6.

The state detecting I / Fs 205 and 207 process encoder outputs and convert them into digital numerical values.
A counter for counting the number of encoder pulses is provided. Further, the state detection I / Fs 205 and 207 utilize the origin information held by the encoder to make the intermediate transfer belt 1
01 and the photoconductor 110 are provided with a function of associating (correlating) each moving position based on the count value.

The belt driving motor 106 is provided with a bus 206 and a driving I for the microcomputer 201.
/ F208 and the driver 209 are connected.
Similarly, the drum drive motor 113 is connected to the microcomputer 201 via the bus 206, the drive I / F 210,
It is connected via a driver 211. The driving I / Fs 208 and 210 are the microcomputer 201.
The digital signal of the calculation result in (1) is converted into an analog signal and given to the drivers 209 and 211 to control the current and voltage applied to the belt driving motor 106 and the drum driving motor 113, respectively.

As a result, the intermediate transfer belt 101 and the photoconductor 110 are driven so as to follow the predetermined target position. Then, the intermediate transfer belt 1 during this drive control
01, the position of the photoconductor 110 is the state detection I / F2
It is taken into the microcomputer 201 via 05 and 207.

The position control method of the belt moving device of this embodiment is executed by the arithmetic processing function of the microcomputer 201. Microcomputer 2
DSP with high numerical processing capability instead of 01
(Digital signal processor) may be used. If the software servo is operated by the single DSP or the single microcomputer, the operation of the controller and the observer, the target value locus, and the feedforward calculation can be processed by the software, and a complicated circuit is not required. Therefore, inexpensive and highly accurate positioning control can be performed.

(Embodiment 1) FIG. 3 is a block diagram showing a configuration relating to position control of a drive target in Embodiment 1 of the present invention. The position control shown in the drawing is executed by the microprocessor 201, and is the content of correction based on the angle of the drive shaft 102 of the intermediate transfer belt 101 which is the drive target. The command 1 of the belt surface target position is directly converted into the drive shaft target position (angle). Belt surface target position command 2 is belt surface position (target surface position)
And the comparison means 301 compares the deviation with the surface position control means 30.
2 is calculated, converted into the drive axis target position (angle), and the addition unit 303 executes the command 1 and the addition. The drive shaft target position (angle) after the addition is calculated by, for example, (1 / (drive shaft radius + belt thickness)).

Then, the deviation between the drive axis target position (angle) and the drive axis angle is obtained by the comparison means 304 and the position control means 305 is obtained.
And the motor to be driven (intermediate transfer belt 101
Belt drive motor 106) of
The drive target is driven following the target position.

If there is no deviation in the surface position, the position of the drive shaft 102 is controlled by command 1, but the intermediate transfer belt 1
When a slip occurs in 01 and eccentricity of the drive shaft 102 causes a deviation in the surface position of the intermediate transfer belt 101, the target angle of the drive shaft 102 is corrected so as to eliminate the generated deviation. As shown in the figure, the drive force transmission system of the drive target is a belt drive motor 10 that outputs a drive shaft angle.
A transmission system from 6 to the angle of the drive shaft 102, and a transmission system from the drive shaft 102 that outputs the surface position of the intermediate transfer belt 101 to the surface position of the intermediate transfer belt 101.

(Embodiment 2) FIG. 4 is a block diagram showing a configuration relating to position control of a driven object in Embodiment 2 of the present invention. Intermediate transfer belt 10 to be driven
The contents of the correction include the drive shaft 102 on the basis of the motor shaft angle of the first belt driving motor 106. The command 1 of the belt surface target position is directly converted into the motor shaft target position (angle). The command 2 of the belt surface target position is compared with the belt surface position (surface target position) by the comparison means 401, and the deviation is calculated by the surface position control means 402, converted into the motor shaft target position (angle), and added by the addition means 403. Command 1
And the addition is executed. The motor shaft target position (angle) after addition is, for example, (rotational speed ratio of drive shaft and motor shaft /
It is calculated by (drive shaft radius + belt thickness).

Then, the deviation between the motor shaft target position (angle) and the motor shaft angle is obtained by the comparison means 404 and the position control means 4 is obtained.
The motor to be driven (intermediate transfer belt 1
No. 01 belt drive motor) is applied as a current, and the drive target is driven following the target position.

If there is no deviation in the surface position, the position of the belt driving motor 106 is controlled by command 1, but slippage on the intermediate transfer belt 101, eccentricity of the drive shaft 102, eccentricity of the drive shaft timing pulley 103, timing belt. Due to the occurrence of misalignment of the core lines of 104, the intermediate transfer belt 1
When a deviation occurs on the surface position 01, the target angle of the motor shaft of the belt driving motor 106 is corrected so as to eliminate the deviation. As illustrated, the transmission system of the driving force in the driven object includes the transmission system from the belt driving motor 106 that outputs the motor shaft angle to the driving shaft 102, and the transmission system up to the motor shaft angle of the belt driving motor 106. And a transmission system from the drive shaft 102 that outputs the surface position of the intermediate transfer belt 101 to the surface position of the intermediate transfer belt 101.

(Third Embodiment) FIG. 5 is a block diagram relating to position control of a drive target according to a third embodiment of the present invention. The belt surface target position and the actual surface position are compared by the comparison means 501, and the deviation is determined by the surface position control means 50.
Calculated by 2. A current is applied to the belt driving motor 106 according to the calculation result, and the driving target is driven following the target position.

As shown in the figure, the drive target in this embodiment is a transmission system from the belt drive motor 106 to the surface position of the intermediate transfer belt 101 which is the drive target. According to the above configuration, the position control of the intermediate transfer belt 101 is
It is possible to perform control based on only the output of the optical sensor (optical head 108) without using the detection output from the drive shaft encoder 109.

FIG. 6 shows the intermediate transfer belt 1 to be driven.
It is a figure which shows the structure of 01. FIG. 6A is a plan view,
(B) is a side view, (c) is the figure seen from the A direction of (b). As illustrated, the intermediate transfer belt 101 has a structure that does not slip with respect to the drive shaft 102.

Intermediate transfer belt 101 and drive shaft 102
Have teeth 601, 6 at one end along the transport direction, respectively.
No. 02 is provided, the teeth of which are meshed with each other, and the rotation of the drive shaft 102 moves the intermediate transfer belt 101. These teeth 601 and 602 are formed on the intermediate transfer belt 101 at positions other than the central image forming portion 603 so that vibrations due to the meshing with each other are not transmitted. Further, belt shift stoppers 604 having steps are formed at both ends of the intermediate transfer belt 101.
1 has a structure that does not move in the axial direction of the drive shaft 102.

Further, the driven shaft 605 is also provided with teeth 606,
In addition to the structure in which the teeth 601 of the intermediate transfer belt 101 are meshed with each other, the driven shaft 605 may be provided with no teeth 606 and a driven shaft 605 that is axially shorter by that amount may be used. Also,
In the illustrated structure, the intermediate transfer belt 101 is a pair of drive shafts 1.
02 and a driven shaft 605, the intermediate transfer belt 101 is provided with a plurality of rollers as shown in FIG. 1, and a roller in the nip portion and other driven shaft rollers (not shown). No.), a short roller without teeth may be used.

As described above, as rollers such as driven shafts other than the drive shaft 102, rollers having a high friction coefficient can be used, such as a roller made of stainless steel coated with polyurethane by dipping. As a result, it is possible to suppress the slip of the intermediate transfer belt in the roller portion other than the drive shaft 102 where the teeth 602 are not formed.

FIG. 7 is a Bode diagram from the motor torque to be driven to the belt surface position. Drive shaft 102
From the torque, the natural frequency (resonance frequency) of the surface position of the intermediate transfer belt 101 Wpd = 25 Hz (157 rad /
s), the natural frequency (resonance frequency) of the transmission system from the belt driving motor 106 torque to the drive shaft 102.
Was 120 Hz (754 rad / s).

FIG. 8 is an open-loop transfer characteristic diagram from the drive shaft target angle to the drive shaft angle including the controller. The crossover frequency Wcd = 30 Hz (188 rad / s). This condition and the resonance frequency Wpd = 25 Hz (157r
In the case of ad / s), the surface position control as described in the first embodiment (see FIG. 3) is performed, and the target drive axis angle is controlled so that there is no deviation from the target surface position of the drive target.

FIG. 9 is an open loop transfer characteristic diagram from the target position to the surface position of the driven object including the controller of the inner feedback loop. Crossover frequency Wcd = 30H
z (188 rad / s), resonance frequency Wpd = 25 Hz
In the case of (157 rad / s), the crossover frequency Wcs = 5H
Since it is z (31 rad / s) and is far from the resonance frequency Wpd = 25 Hz (157 rad / s) of the intermediate transfer belt 101 on the low frequency side, stable control can be realized. Further, by satisfying the condition of crossover frequency Wcd> crossover frequency Wcs, the inner feedback loop can realize the control with fast response. Further, since the slope of the crossover frequency Wcs has an integration characteristic of −20 db / oct, stable position control can be realized.

(Fourth Embodiment) FIG. 10 shows a fourth embodiment.
3 is a block diagram relating to position control of a driving target of FIG. The configuration shown in the figure includes each component described in FIG. 3, and a disturbance estimation observer 1002 is added to the PI controller 1001 as the position control unit 305.

The deviation between the drive axis target position (angle) and the drive axis angle is obtained by the comparison means 304, and the PI controller 100
1 and the motor to be driven (intermediate transfer belt 10
1 is given as a current to the belt driving motor 106), and is added to the output of the disturbance estimation observer 1002 by the adding means 1003, and then supplied to the drive target, and is driven following the target position.

The disturbance estimation observer 1002 converts the estimated amount of acceleration disturbance into a motor disturbance estimation current id based on the drive shaft angle and the output of the addition means 1003, and adds it to the addition means 10.
Output to 03.

The transfer function PICON (S) of the PI controller 1001 that controls the drive shaft 102 is shown in equation (1).

[0089]   PICON (S) = (T11 * S + 1) / (T12 * S + 1) * btgac * bhcf2 * bhcf2 (1)   T11 = 1 / (Wcd / sqrt (10)) (2)   T12 = 1 / (Wcd * sqrt (10)) (3)   bhcf2 = 1 / (S / (Wcd * 4) +1) (4)   btgac = 1 / abs (T11 * j * Wcd + 1) * abs (T12 * j *   Wcd + 1) * abs (btJt * btgear / btkt * j * Wcd * j * Wcd) (5)

However, S is a Laplace operator. sqrt
() Is the square root of (). abs () is the absolute value of (). j is sqrt (-1). btJt is a moment of inertia equivalent to the motor axis of the drive target. btgear is
The ratio of the number of teeth on the motor shaft pulley and the drive shaft pulley. btk
t is the torque constant of the motor. Wcd = 30 Hz (188 rad / s), btJt =
1.578 * 10-4, btgear = 4, btkt =
0.078

From the target drive axis angle, the controller P
FIG. 8 shows the open-loop transfer characteristic up to the drive shaft angle including ICON (S). Crossover frequency Wcd = 30 Hz (188
rad / s). -40 dB / oc below 10 Hz
slope of t, −40 dB / o from 90 Hz to 120 Hz
The slope of ct has a slope of −80 dB / oct at 120 Hz or higher, and by lowering the gain in the high range, the natural frequency (resonance frequency) of the transmission system from the motor torque to the drive shaft is 120 Hz (754 rad / s). The instability phenomenon of is avoided.

The disturbance estimation observer in FIG. 10 will be described. Letting the disturbance be an acceleration disturbance, the state equation of the timing belt system driven object including the acceleration disturbance is expressed by equation (6),
It shows in (7).

[0093]

[Equation 1]

V: velocity, x: drive axis angle, w: acceleration disturbance, i: motor current Gopinus canonical form of the minimum dimension observer is obtained. The observer poles are γ1 = -300, γ2 = -299.
The equation of state of the minimum-dimensional disturbance observer is
Expressions (8) and (9) are obtained.

[0095]

[Equation 2]

From the above, the disturbance estimation observer 1002
Feeds back the motor disturbance estimated current to the adding means 1003 from the drive shaft angle and the motor current. FIG. 11 shows
It is a figure which shows the comparison of the position deviation in the case where the disturbance estimation observer 1002 is provided, and the case where it is not provided. The horizontal axis represents time (seconds) and the vertical axis represents position deviation (m). If there is a periodic disturbance of 10 Hz, the position variation from −50 μm to +50 μm occurs if the disturbance estimation observer 1002 is not provided. However, by providing the disturbance estimation observer 1002,
The position variation can be changed from −20 μm to +20 μm, and the position variation can be suppressed to 2/5 as compared with the case where it is not provided. In addition, overshoot can be suppressed even with respect to step disturbance.

(Fifth Embodiment) FIG. 12 shows a fourth embodiment.
3 is a block diagram relating to position control of a driving target of FIG. The configuration shown in the drawing is the PI controller 1 described in FIG.
001, a disturbance estimation observer 1002 is provided, and in addition, a feedforward system 1201 is added.

In FIG. 12, the reference signal Refposi
(S) is a ramp function of Refposi (s) = vref / s. s is a Laplace operator. The target value transfer function Gref (s) is: Gref (s) = 1 / (a3 * sigma3 * s3 + a2 * sigm2 * s2 + a1 * sigma * s + 1) (11)

[0099]   However, sigma = 0.095 * 2 (12)   alpha = 0.2 * 2 (13)   a1 = (1-alpha) + alpha (14)   a2 = (1-alpha) * 0.3333 + alpha * 0.3786 ... ( 15)   a3 = (1-alpha) * 0.003704 + alpha * 0.1006 … (16) Is.

Transfer function Gno of controlled object excluding vibration term
m (s) Gnom (s) = btkt * 1 / btJt * 1 / btgear * 1 / s2 (17)

In FIG. 12, the feedforward current Iff is: Iff = Refposi (s) * Gref (s) / Gnom (s) / (drive shaft radius + belt thickness) (18)

FIG. 13 is a diagram showing a comparison of drive shaft speeds with and without the feedforward system 1201 at the start of movement of the intermediate transfer belt 101. The horizontal axis represents time (seconds) and the vertical axis represents velocity (rad /
s). When the feedforward system 1201 is provided, as shown in the drawing, the target speed can be smoothly reached without overshoot, and the vibration of the device can be suppressed.

FIG. 14 is a diagram showing the results at the time of belt slip in the case of the transfer characteristic shown in FIG. 9, that is, when the feedback of the drive shaft 102 and the feedback control for the belt surface position of the intermediate transfer belt 101 are implemented. is there. At this time, the intermediate transfer belt 101 is about 200 μ
It is assumed that slippage has occurred and a positional deviation has occurred. As shown in the drawing, when the time is 0.8 seconds, the positional deviation occurs, but after 0.2 seconds, the position deviation is almost eliminated. In this way, the effect of monitoring and feeding back the displacement of the surface position has appeared.

(Sixth Embodiment) FIG. 15 is a block diagram showing a signal interpolation circuit according to a sixth embodiment of the present invention. The signal interpolating circuit 1501 temporally interpolates the pulses output from the optical sensor (optical head 108) with a constant interval clock.

The signal interpolating circuit 1501 can be constituted by, for example, a counter which counts a reference clock having a cycle shorter than that of the pattern detection signal by using the edge of the pattern detection signal as a trigger. The microcomputer 201
Is the count value of the pattern detection signal output from the optical sensor (optical head 108) and the count value of the signal interpolation signal output from the signal interpolation circuit 1501, and calculates the position of the intermediate transfer belt 101 at the moment of loading. To do.

In a feedback system using a general encoder or the like, an encoder counter is used, and a position / angle or the like is calculated from the count value at the time when the controller reads the count value, and is compared with the target value. However, the count value of the counter has uncertainty for the pulse period. For example, a pulse corresponding to a period of 0.1 mm causes an error of maximum 0.1 mm, which may cause unstable control. In this embodiment, for example, a clock corresponding to a cycle of 0.001 mm is used to regard the pattern signal cycle as a constant speed for interpolation. By doing so, the position detection error can be suppressed to the error of the speed fluctuation.

The position control operation using this signal interpolation circuit 1501 will be described. The signal interpolation circuit 1501
Pattern signal counter 1502 and clock counter 1
These counters can be configured by a general counter having a gate (GATE) and a source (SOUCE) input, and these count values are captured by the image signal generation unit 1504.

GATE of the pattern signal counter 1502
For each rotation of the intermediate transfer belt 101 (every time the optical head 108 detects the encoder scale 107)
The origin signal generated once or a signal from the machine body is input and used to start counting. The pattern detection signal is input to the SOURCE signal of the pattern signal counter 1502. A pattern signal is input to GATE of the clock counter 1503, and an interpolation clock is input to SOUCE.

According to the above configuration, for example, when the pattern interval is 0.1 mm and the pattern signal is about 1 kHz and the pattern signal fluctuates by about 1% due to the speed fluctuation, the control using the interpolation clock of 100 kHz is performed. When the motor is controlled, the counter data is fetched, the internal calculation and the motor drive output are looped, so the reading of the counter data varies depending on the processing speed.

Therefore, when the value of the pattern counter is read and the value is 10 counts,
The position may be 1 mm to 1.1 mm.
Therefore, the clock counter is read, and if the value is 50 counts, the average speed is 100 m for motor control.
100 (mm / s) x 50 (count) / 1 from m / s
The 00k (Hz) clock counter portion is determined to be 0.05 mm, and it is calculated that the position is 1.05 mm as a whole. If the fluctuation of the average speed is 1%, the error of the clock counter is within 1%, and therefore 0.0499 to 0.050.
Since it is 1 mm, highly accurate detection can be performed.

Next, FIG. 16 is a schematic configuration diagram of an image forming unit of a color copy or color printer provided with the intermediate transfer belt 101 described in each of the above embodiments. The color copying machine includes an image forming unit 1600 shown in the figure, a color image reading unit (hereinafter referred to as “color scanner”), a paper feeding unit, and a control unit for driving and controlling these, not shown.

The color scanner reads the color image information of the original for each color-separated light of red, green, and blue (hereinafter referred to as “R”, “G”, and “B”), and an electrical image signal is obtained. Convert to. Then, based on the intensity levels of the R, G, and B color-separated image signals obtained by this color scanner, color conversion processing is performed by an image processing unit (not shown), and black, cyan, magenta, and yellow (hereinafter, respectively, Image data of “Bk”, “C”, “M”, and “Y”) are obtained.

The image forming unit 1600 of FIG. 16 includes a photoconductor (drum) 110 as an image carrier, a charger 1601 as a charging unit, a photoconductor cleaning device 1602 including a cleaning blade and a fur brush,
A writing optical unit (not shown) as an exposing unit, a revolver developing unit 1603 as a developing unit, an intermediate transfer unit 1604, a secondary transfer unit 1620, and a fixing unit (not shown) using a pair of fixing rollers are included.

The photoconductor drum 110 rotates counterclockwise as shown by the arrow in the figure, and around the periphery thereof, the electrified charger 1601, the photoconductor cleaning device 1602, the revolver developing unit 1603, and the selected developing device, The intermediate transfer belt 101 as an intermediate transfer member of the intermediate transfer unit 1604 is arranged. Further, the writing optical unit converts the color image data from the color scanner into an optical signal, and applies the laser light L corresponding to the image of the original on the surface of the photosensitive drum 110 uniformly charged by the charging charger 1601. Irradiation is performed to perform optical writing to form an electrostatic latent image on the surface of the photoconductor drum 110.
This writing optical unit can be configured by, for example, a semiconductor laser as a light source, a laser emission drive control unit, a polygon mirror and its rotation motor, an f / θ lens, a reflection mirror, and the like.

Also, the revolver developing unit 1603.
Is a Bk developing machine 1611 using Bk toner, a C developing machine 1612 using C toner, an M developing machine 1613 using M toner, a Y developing machine 1614 using Y toner, and a developing revolver for rotating the entire unit in a counterclockwise direction. It is configured by a drive unit (not shown) and the like. Each developing machine 1 installed in this revolver developing unit 1603
Reference numerals 611 to 1614 denote a developing sleeve as a developer bearing member that rotates by bringing a brush of the developer into contact with the surface of the photoconductor drum 110 to develop the electrostatic latent image, and to scoop up and stir the developer. It is composed of a rotating developer paddle, a developing sleeve drive unit for rotating the developing sleeve in a clockwise direction indicated by an arrow, and the like.

The toner in each of the developing devices 1611 to 1614 having the above-described structure is charged with a negative polarity by stirring with the ferrite carrier, and each developing sleeve is supplied with a negative direct current by a developing bias power source as a developing bias applying means (not shown). A developing bias voltage in which an AC voltage Vac (AC component) is superimposed on the voltage Vdc (DC component) is applied, and each developing sleeve is biased to a predetermined voltage with respect to the metal base layer of the photosensitive drum 110.

In the standby state of the color copying machine main body, the revolver developing unit 1603 is stopped at the home position where the Bk developing machine 1611 is located at the developing position, and when the copy start key of the image forming apparatus is pressed, the original image is displayed. Data reading is started, and based on the color image data, optical writing by the laser light L, that is, electrostatic latent image formation is started (hereinafter, the electrostatic latent image based on the Bk image data is referred to as “Bk electrostatic latent image”). The same applies to C, M and Y).

In order to enable development from the tip of the Bk electrostatic latent image, before the tip of the electrostatic latent image reaches the Bk developing position, the rotation of the Bk developing sleeve is started and the Bk electrostatic latent image is started. Is developed with Bk toner. Then, the developing operation of the Bk electrostatic latent image is continued thereafter, but when the rear end portion of the Bk electrostatic latent image passes the Bk developing position, the revolver is promptly moved until the developing machine of the next color comes to the developing position. The developing unit 1603 rotates. This rotation is completed at least before the leading end of the electrostatic latent image formed by the next image data reaches the developing position.

The intermediate transfer unit 1604 is composed of the intermediate transfer belt 101 stretched around the plurality of rollers described above. Around this intermediate transfer belt 101,
A secondary transfer belt 1605 which is a transfer material carrier of the secondary transfer unit 1620, a secondary transfer bias roller (paper transfer roller) 115 which is a secondary transfer charge applying unit, and a belt cleaning blade 1 which is an intermediate transfer member cleaning unit.
616, a lubricant application brush 161 as a lubricant application means
7 and the like are arranged so as to face each other.

The intermediate transfer belt 101 includes a primary transfer bias roller 1625 which is a primary transfer charge imparting means, a belt drive roller (drive shaft described above) 102, a belt tension roller 1626, a secondary transfer counter roller 1627,
The cleaning counter roller 1628 and the earth roller 1629 are stretched. Each roller is formed of a conductive material, and each roller other than the primary transfer bias roller 1625 is grounded.

The primary transfer bias roller 1625 has a transfer bias controlled by a primary transfer power source 1631 controlled by a constant current or a constant voltage to a current or voltage of a predetermined magnitude according to the number of superposed toner images. Is being applied. Further, the intermediate transfer belt 101 is driven in the arrow direction by a belt driving motor 106 (see FIG. 1) via a drive shaft timing pulley 103 and a timing belt 104. The intermediate transfer belt 101 is a semiconductor or an insulator and has a single-layer or multi-layer structure.

At the transfer portion (hereinafter referred to as “primary transfer portion”) for transferring the toner image on the photoconductor (drum) 110 to the intermediate transfer belt 101, the intermediate transfer belt 101 is made up of the primary transfer bias roller 1625 and the earth roller 1629. Is stretched so as to be pressed against the photoconductor (drum) 110 side, whereby the photoconductor (drum) 110 and the intermediate transfer belt 1 are
A nip portion having a predetermined width is formed between the nip portion 01 and the groove No. 01.

The lubricant application brush 1617 is for polishing zinc stearate 1618 as a lubricant formed in a plate shape and applying the polished fine particles to the intermediate transfer belt 101. This lubricant coating brush 1617 also
The intermediate transfer belt 101 is configured so as to be adjacent to the intermediate transfer belt 101, and is controlled to come into contact with the intermediate transfer belt 101 at a predetermined timing.

The secondary transfer unit 1620 is composed of a secondary transfer belt 1605 stretched around three supporting rollers 1632, 1633 and 1634, and the supporting roller 163.
The tension between 2 and 1633 is 2 of the intermediate transfer belt 101.
It can be pressed against the next transfer counter roller 1627. One of the three support rollers 1632, 1633, 1634 is a drive roller that is rotationally driven by a drive unit (not shown), and the drive roller drives the secondary transfer belt 1605 in the direction indicated by the arrow in the figure.

The secondary transfer bias roller 115 is a secondary transfer means and is disposed so as to sandwich the intermediate transfer belt 101 and the secondary transfer belt 1605 between it and the secondary transfer counter roller 1627, and constant current control is performed. Secondary transfer power supply 16
A transfer bias of a predetermined current is applied by 35. In addition, the secondary transfer belt 1605 and the secondary transfer bias roller 115 are connected to the secondary transfer counter roller 1627.
A separation / contact mechanism (not shown) that drives the support roller 1632 and the secondary transfer bias roller 115 in the direction of the arrow is provided so as to be able to take a position where they are pressed against and a position where they are separated. In the figure, the separated position of the secondary transfer belt 1605 and the support roller 1632 is shown by a chain double-dashed line.

Reference numeral 1650 denotes a pair of registration rollers, which is a secondary transfer bias roller 115 and a secondary transfer counter roller 162.
The transfer sheet P, which is a transfer material, is fed at a predetermined timing between the intermediate transfer belt 101 and the secondary transfer belt 1605 sandwiched between the sheet and the sheet. In a portion of the secondary transfer belt 1605 stretched by a support roller 1633 on the side of a fixing roller pair (not shown), a transfer sheet charge removing charger 1656 which is a transfer material charge eliminating means and a belt which is a transfer material carrier charge eliminating means. The antistatic charger 1657 faces. A cleaning blade 1658, which is a transfer material carrying member cleaning means, is in contact with a portion of the secondary transfer belt 1605 that is stretched around a lower support roller 1634 in the drawing.

The transfer sheet charge eliminator 1656 removes the electric charge held on the transfer sheet so that the transfer sheet can be satisfactorily separated from the secondary transfer belt 1605 by the strength of the transfer sheet itself. is there. The belt charge removal charger 1657 removes charges remaining on the secondary transfer belt 1605. Also, the cleaning blade 1658 removes and cleans the adhering substances adhering to the surface of the secondary transfer belt 1605.

In the color copying machine thus constructed, when the image forming cycle is started, the photosensitive drum 1
The drum drive motor 113 (see FIG. 1) rotates the drum 10 in a counterclockwise direction indicated by an arrow, and the intermediate transfer belt 10 is rotated.
1 is rotated clockwise by a belt driving roller (driving shaft) 102 as indicated by an arrow. With the rotation of the intermediate transfer belt 101, Bk toner image formation, C toner image formation, M toner image formation, and Y toner image formation are performed by the transfer bias by the voltage applied to the primary transfer bias roller 1625.
Next transfer is performed, and finally, a toner image is formed in the order of Bk, C, M, and Y on the intermediate transfer belt 101.

For example, Bk toner image formation is performed as follows. The charging charger 1601 uniformly charges the surface of the photoconductor drum 110 with a negative charge to a predetermined potential by corona discharge. Then, a writing optical unit (not shown) performs raster exposure with laser light based on the Bk color image signal. When this raster image is exposed, in the exposed portion of the surface of the photoconductor drum 110 that is initially uniformly charged, the charge proportional to the amount of exposure light disappears, and a Bk electrostatic latent image is formed.

On this Bk electrostatic latent image, a Bk developing machine 1611
Since the negatively charged Bk toner on the Bk developing roller comes into contact with the Bk developing roller, the toner does not adhere to the portion of the photosensitive drum 110 where the electric charge remains, and the toner does not adhere to the uncharged portion, that is, the exposed portion. Bk that attracts and is similar to an electrostatic latent image
A toner image is formed. The Bk toner image formed on the photoconductor drum 110 is transferred to the surface of the intermediate transfer belt 101 that is in constant contact with the photoconductor drum 110 and is being driven at a constant speed. Such transfer of the toner image from the photoconductor drum 110 to the intermediate transfer belt 101 is called “belt transfer”.

A small amount of untransferred residual toner remaining on the surface of the photoconductor drum 110 after the belt transfer is cleaned by the photoconductor cleaning device 1602 in preparation for reuse of the photoconductor drum 110. On the photoconductor drum 110 side,
After the Bk image forming process, the C image forming process is performed, and the C scanner starts reading the C image data by the color scanner at a predetermined timing. Form an image.

Then, after the trailing end of the previous Bk electrostatic latent image has passed and before the leading end of the C electrostatic latent image has arrived, the revolver developing unit 1603 is rotated,
The C developing machine 1612 is set to the developing position, and the C electrostatic latent image is developed with C toner. After that, the development of the C electrostatic latent image region is continued, but when the rear end of the C electrostatic latent image passes, the revolver developing unit 1603 is rotated like the case of the Bk developing machine 1611. Next M developing machine 16
13 is moved to the developing position. This is also completed before the leading edge of the next M electrostatic latent image reaches the developing position. It should be noted that in the M and Y image forming steps, the operations of reading color image data, forming an electrostatic latent image, and developing are the same as the steps Bk and C described above, and therefore description thereof will be omitted.

On the intermediate transfer belt 101, Bk, C, M, and Y toner images sequentially formed on the photosensitive drum 110 are sequentially aligned and transferred to the same surface. As a result, a toner image in which a maximum of four colors are superimposed is formed on the intermediate transfer belt 101.

At the time when the image forming operation is started, the transfer sheet P is fed from a sheet feeding unit such as a transfer sheet cassette or a manual feed tray (not shown), and the registration roller pair 1650.
Waiting at the nip. Secondary transfer counter roller 1627
Also, when the tip of the toner image on the intermediate transfer belt 101 reaches the secondary transfer portion where the nip is formed by the secondary transfer bias roller, the registration is performed so that the tip of the transfer paper P coincides with the tip of the toner image. Roller pair 16
50 is driven, and registration of the transfer paper P and the toner image is performed.

Then, the transfer paper P is the intermediate transfer belt 101.
It passes through the secondary transfer portion while being superimposed on the upper toner image. At this time, by the transfer bias of the voltage applied to the secondary transfer bias roller 115 by the secondary transfer power supply 1635,
The four-color superposed toner images on the intermediate transfer belt 101 are collectively transferred onto the transfer paper.

When the secondary transfer belt 1605 passes through a portion facing the transfer sheet charge eliminator charger 1656 arranged on the downstream side of the secondary transfer portion in the moving direction, the transfer sheet P
Is removed from the secondary transfer belt 1605 and sent toward a fixing roller pair (not shown). The toner image is fused and fixed at the nip portion of the fixing roller pair (not shown), sent out of the apparatus main body by the not-illustrated discharge roller pair, and stacked face up on the not-shown copy tray,
Get a full color copy.

On the other hand, the photosensitive drum 1 after the above belt transfer
The surface of 10 is cleaned by the photoconductor cleaning device 1602, and is uniformly discharged by a discharging lamp (not shown). Further, the toner remaining on the surface of the intermediate transfer belt 101 after the toner image is transferred onto the transfer paper P is cleaned by a belt cleaning blade 1616 pressed against the intermediate transfer belt 101 by a separating / contacting mechanism (not shown).

Here, at the time of repeat copying, the operation of the color scanner and the image formation on the photosensitive drum 110 are continued after the image forming process of the fourth color (Y) of the first sheet.
The image forming process for the first color (Bk) of the second sheet proceeds at a predetermined timing. Further, in the case of the intermediate transfer belt 101, following the batch transfer process of the first four-color superimposed toner image onto the transfer paper, the belt cleaning blade 1616 on the front surface is used.
The second Bk toner image is belt-transferred to the area cleaned by. After that, the same operation as the first sheet is performed.

The above is the copy mode for obtaining the four-color full-color copy. However, in the case of the three-color copy mode and the two-color copy mode, the same operation as described above is performed for the designated color and the number of times. Become. In the case of the single-color copy mode, until the predetermined number of sheets is completed, only the developing device of the predetermined color of the revolver developing unit 1603 is in the developing operation state and the belt cleaning blade 1616 is pressed against the intermediate transfer belt 101. The copy operation is performed with the position as it is.

Next, FIG. 17 is a diagram showing a configuration example of a tandem image forming apparatus. The intermediate transfer belt 101 is roughly composed of a driving roller (driving shaft) 102 and a driven roller 170.
1, tension roller 1702 and the like.
On the moving direction of the intermediate transfer belt 101, each color CMYK
Another four photoconductor drums 110 (110a to 110d)
Are arranged. Each of these photosensitive drums 110,
They are driven by independent drum drive motors and transmission mechanisms (not shown). The positional relationship among the photoconductor drum 110, the intermediate transfer belt 101, and the writing optical system is arranged at a target position with respect to the center of the photoconductor drum 110.

Even in such a configuration, by performing the movement control described in the above embodiment on the intermediate transfer belt 101, highly accurate position control can be performed, and there is no color misregistration in each color and high quality is achieved. Image formation can be performed.

The processing contents of the movement control described in this embodiment can be realized by executing a prepared program on a computer such as a personal computer or a workstation. This program is recorded on a computer-readable recording medium such as a hard disk, a floppy (R) disk, a CD-ROM, an MO, or a DVD, and is executed by being read from the recording medium by the computer. The program can be distributed via the recording medium and a network such as the Internet.

[0143]

As described above, according to the first aspect of the invention, the drive shaft for moving the belt and the transmission means for transmitting the drive force from the motor to the drive shaft are provided, and In a belt moving device that moves a belt by a driving force from a motor, a marker detecting unit that detects a marker provided on the belt for recognizing a position in the moving direction of the belt, and a rotation state of the drive shaft are detected. Rotation state detecting means, first correction information creating means for creating correction information for correcting the position of the belt in the moving direction based on the detection result of the marker detecting means, and the detection result of the rotating state detecting means. Based on the correction information of the first and second correction information creating means, and second correction information creating means for creating correction information for correcting the rotation state of the drive shaft. Because and control means for moving controlling the motor have, belt and drive shaft slips,
When the belt deviates from the target position, by detecting the position of the belt surface, the rotational shaft target position of the drive shaft can be corrected by the amount of the belt deviation to return the position of the belt surface to the position where there is no slip. When the belt deviates from the target position due to the eccentricity of the drive shaft, the position of the belt surface is measured, and the target position of the drive shaft rotation angle is corrected by the amount of the belt deviation to adjust the belt surface position to the eccentricity of the drive shaft. It can be returned to its original position. As a result, it is possible to suppress the displacement of the belt from the target position.

According to a second aspect of the present invention, in the first aspect of the invention, the first correction information creating means sets the maximum response frequency of the correction information created by the second correction information. Since the frequency is set to be smaller than the maximum response frequency of the correction information created by the information creating unit, in the position control of the belt having low rigidity, the response frequency is set low to prevent the resonance from being excited. The drive system from the motor to the drive shaft, which has higher rigidity than the belt, increases the response frequency and performs position control to cancel the eccentric disturbance of each shaft. The belt shift is
The first correction means and other disturbances are mainly taken care of by the second correction means, so that the positional deviation from the belt target position can be suppressed.

According to the third aspect of the invention, in the belt moving device for driving the belt by rotating the drive shaft by driving the motor, the detecting means for detecting the surface position of the belt, and the detecting means. Since it has a position control means for feeding back the surface position detected by the method to make the surface position of the driven object follow the target position, the rigidity of the belt is increased to increase the resonance frequency of the belt and increase the control band. By directly feedback-controlling the belt surface position, it is possible to suppress the displacement from the belt target position.

According to the fourth aspect of the invention, in the belt moving device for driving the belt by rotating the drive shaft by driving the motor, the rotation state detecting means for detecting the rotation state of the motor shaft, A control unit that feeds back the rotation state detected by the rotation state detection unit and performs a movement control that causes the motor shaft target position to follow the target position of the motor shaft so that there is no deviation from the target surface position of the belt; Because of the feedback of the rotation state of the motor shaft, the mechanical error such as eccentricity of the transmission system from the motor shaft to the drive shaft position, the mechanical error such as eccentricity of the transmission system from the drive shaft to the belt surface position, and the belt If the drive roller slips, the position of the belt surface is detected and the target position of the rotation angle of the motor shaft is corrected by the amount of belt deviation to correct the belt surface. Back to the position when there is no slip location, an effect that it is possible to suppress the positional deviation of the belt target position.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, a tooth is provided at least at one position in the axial direction of the drive shaft on which the belt is stretched. Since the belt is formed with teeth that mesh with the teeth of the drive shaft, and the belt is moved by the rotation of the drive shaft, the belt and the drive shaft mesh with each other, so that the displacement from the target position is suppressed. There is an effect that can be.

According to the invention described in claim 6, in the invention described in any one of claims 1 to 4, the drive surface of the drive shaft is provided with a member having a large friction coefficient,
Since the belt is moved by the rotation of the drive shaft, the slip of the belt can be reduced, and the positional deviation from the target position can be suppressed.

According to a seventh aspect of the present invention, in the invention according to any one of the first to sixth aspects, the belt is an intermediate transfer belt provided in an image forming apparatus and / or a paper conveying device. Since the belt is used, it is possible to prevent positional deviation during image formation in the image forming apparatus and to perform highly accurate image formation.

Further, according to the invention described in claim 8, in the invention described in any one of claims 1 and 2, the control means drives from a target drive shaft angle with respect to the drive shaft including a controller. When the relationship between the crossover frequency Wcd of the open-loop transfer characteristic up to the shaft angle and the natural frequency Wpd from the drive shaft torque to the surface position of the belt is Wcd> Wpd, the target drive shaft angle is set to the target of the belt. Since the control is performed so that there is no deviation from the surface position, when the rigidity from the motor generated torque to the drive shaft angle is high and the rigidity from the drive shaft torque to the belt surface position is low, that is, the motor generated torque drives Open loop from the target drive axis angle to the drive axis angle including the controller when the resonance frequency up to the axis angle is higher than the drive shaft torque to the belt surface position The crossover frequency Wcd of the transfer characteristic can be increased, and a stable and fast responsive control system can be configured. Also, the deviation from the target surface position of the belt is
By adding it to the target drive axis angle, it can be eliminated, so that an effect that the positional deviation can be suppressed can be obtained.

According to the invention of claim 9, in the invention of claim 4, the control means is a motor including a mechanical system from a target motor shaft angle to the drive shaft to a controller and the drive shaft. When the relationship between the crossover frequency Wcm of the open-loop transfer characteristic up to the shaft angle and the natural frequency Wpd from the drive shaft torque to the surface position of the belt is Wcm> Wpd, the target motor shaft angle is set to the target of the belt. Since the control is performed so that there is no deviation from the surface position, the rigidity from the motor generated torque to the motor shaft angle is high, and the rigidity from the drive shaft torque to the belt surface position is low, that is, the motor generation. When the resonance frequency from the torque to the motor shaft angle including the mechanical system from the drive shaft is higher than the drive shaft torque to the belt surface position, the target motor shaft angle Since it is possible to increase the crossover frequency Wcm of the open-loop transfer characteristic from the degree to the motor shaft angle including the controller, it is possible to configure a stable and responsive control system. Further, the deviation of the belt from the target surface position can be eliminated by adding it to the target motor shaft angle, and the effect of reducing the position deviation can be obtained.

According to the invention described in claim 10,
In the invention according to claim 3, the control means uses the cross frequency Wcs of the open loop transfer characteristic from the target position to the surface position of the belt including the controller and the surface position of the belt from the drive shaft torque or the motor shaft torque. When the relation of the natural frequency Wpdm up to is Wpdm> Wcs and stable control is possible, the surface position of the belt is fed back to control so as to eliminate the deviation from the target surface position of the belt. Because I did
Even if the belt has a high rigidity, feedback control of the surface position of the belt can realize control with excellent responsiveness and stability, and can eliminate the deviation from the target surface position of the belt.

According to the invention described in claim 11,
The invention according to any one of claims 1, 2 and 8, wherein the control means feeds back a rotation state of the drive shaft detected by the rotation state detection means to follow a drive shaft target position. The relationship between the crossover frequency Wcd of the feedback loop and the crossover frequency Wcs of the open loop transfer characteristic from the target position to the surface position of the belt including the controller of the inner feedback loop is such that the control of the outer feedback loop is Wcd> Wcs. Since the configuration is performed, when the resonance frequency from the drive shaft to the belt surface position is low for the target drive shaft angle, the gain of the outer feedback loop is suppressed, and the target drive shaft angle can be changed stably. Play.

Further, according to the invention of claim 12,
The invention according to any one of claims 4 and 9, wherein the control means feeds back a rotational state of the drive shaft detected by the rotational state detection means to follow a drive shaft target position. Of the crossover frequency Wcm of the open loop transfer characteristic from the target position to the surface position of the belt including the controller of the inner feedback loop to execute the control of the outer feedback loop with Wcm> Wcs. Because of the configuration, when the transmission frequency from the motor to the drive shaft or the resonance frequency from the drive shaft to the belt surface position is low, the gain of the outer feedback loop is suppressed to stabilize the target motor shaft angle. There is an effect that can be changed.

Further, according to the invention of claim 13,
In the invention according to any one of claims 1 to 4, 10 to 12, the control means is configured by adding a disturbance estimation observer to a PI controller, and is an open loop from a target position to a surface position of the belt. Crossover frequency W of transfer function
Since the slope of cs has an integration characteristic of -20db / dec, the minor loop is
The PI controller performs stable position control, and the disturbance estimation observer performs high-precision position control for position fluctuations due to disturbances that cannot be removed by position control. Therefore, the outer feedback loop, that is, from the target position to the belt surface position By setting the slope of the crossover frequency Wcs of the open-loop transfer function of -20 dB / dec as the integral characteristic, it is possible to achieve stable position control in the entire system.

Further, according to the invention of claim 14,
In the invention according to any one of claims 1 to 4, 10 to 13, as the control means, a new target position is obtained by multiplying a target position of a ramp function by a function that smoothes the target position at the start of driving of the belt. As a comparison signal of the measured output, a feedforward system circuit that feeds a feedforward current to the motor by multiplying the function for smoothing the target position by the reciprocal of the transfer function of the controlled object is provided. At the start, since the target position of the ramp function is multiplied by a function for smoothing, there is an effect that the position control with a small overshoot and vibration can be executed.

Further, according to the invention of claim 15,
In the invention according to claim 5, since the teeth are formed on the belt at a position other than the image forming portion, vibration due to the teeth is not transmitted to the image forming portion, and banding and positional deviation are reduced. There is an effect that can be.

Further, according to the invention of claim 16,
In the invention according to any one of claims 5 and 7, the belt is stretched between the drive shaft and a plurality of rollers,
Since at least the roller of the transfer nip portion of the plurality of rollers has an axial length that does not contact the teeth of the belt, the teeth do not contact the transfer nip portion of the belt, so that vibration due to the teeth is transmitted to the image forming portion. In addition, it is possible to reduce banding and displacement.

According to the invention of claim 17,
In the invention according to any one of claims 1 to 16,
Since the transmission means from the motor to the drive shaft is composed of the timing belt and the timing pulley, the belt is less likely to be displaced relative to the drive shaft, and the noise is smaller than that of the gear drive, and the consumption is less than that of the direct drive. This has the effect of suppressing power consumption.

Further, according to the invention of claim 18,
In the invention according to any one of claims 1 to 16,
Since the transmission means from the motor to the drive shaft is composed of gears, the belt is less likely to be displaced with respect to the drive shaft, and the rigidity can be increased compared to the timing belt and timing pulley drive, and direct drive is possible. Compared with this, there is an effect that power consumption can be suppressed.

According to the invention of claim 19,
In the invention according to any one of claims 1 to 16,
Since the transmission means from the motor shaft to the drive shaft is a direct drive in which the motor shaft and the drive shaft are integrated or the motor shaft and the drive shaft are fastened by a coupling, the belt is not displaced with respect to the drive shaft. Further, compared to a transmission system including a timing belt and a timing pulley or a transmission system including a gear, noise is reduced and rigidity can be increased.

According to the invention of claim 20,
In the invention according to any one of claims 1 to 19,
The control means performs A / D conversion on the marker composed of the slit pattern detected by the marker detection means,
Since the signal interpolating means for interpolating the position between the slit patterns indicated by the detected marker based on the output of the D / D conversion is provided, even if an inexpensive marker detecting means having a wide slit pattern is used, By performing analog-to-digital conversion on the detected analog output and interpolating between the slits, high resolution can be achieved and highly accurate position control can be achieved.

Further, according to the invention of claim 21,
In the invention according to any one of claims 1 to 20,
Since the control means includes a signal interpolating means for temporally interpolating between the pulse edges of the signal pulse of the marker formed of the slit pattern detected by the marker detecting means with a constant interval clock having a shorter period than the signal pulse, Even if an inexpensive marker detection means having a wide slit pattern is used, the resolution is improved by temporally interpolating between the pulse edges of the slit detection with a constant interval clock having a shorter cycle than the signal pulse. This makes it possible to achieve high precision position control.

Further, according to the invention of claim 22,
In the invention according to any one of claims 1 to 21,
Since the control means drives and controls the belt by using a single DSP or a single microcomputer, a single DSP or a single CPU executes software servo, so that a controller or an observer operates. The target value locus and feedforward calculation can be processed by software, and there is an effect that a complicated circuit is not required, the cost is low, and highly accurate positioning control can be performed.

Further, according to the invention of claim 23,
23. In the invention according to claim 22, the control means gives a calculation result discretized at a sampling time of a control calculation as an input to the motor for the calculation of the servo drive using the DSP or the microcomputer. Therefore, using the software servo, the PI controller, disturbance estimation observer,
Since the new target position and feedforward value are discretized and calculated, there is an effect that highly accurate positioning control can be performed.

Further, according to the invention of claim 24,
In the invention according to any one of claims 1 to 23,
Since the rotation state detecting means is an eccentricity correction encoder provided coaxially with the drive shaft or the shaft of the motor, even if eccentricity occurs in the encoder attached to the drive shaft or the motor shaft, the eccentricity can be corrected. The position error of the drive shaft and the motor shaft can be controlled with high accuracy without causing a position error.

Further, according to the invention of claim 25,
The belt moving device according to any one of claims 1 to 24 is provided, the belt moving device is provided as an intermediate transfer belt for forming the belt image, and the intermediate transfer belt is moved and controlled to transfer a color image of a plurality of colors. Since the image forming means for forming an image on the paper is provided, the movement control of the intermediate transfer belt can be performed with high accuracy, so that the color misregistration of the color image on the transfer paper can be prevented and a high quality image can be formed. Produce an effect.

[Brief description of drawings]

FIG. 1 is a perspective view showing an overall configuration of a belt moving device according to the present invention.

FIG. 2 is a block diagram showing a drive system of a moving mechanism of an intermediate transfer belt in a belt moving device.

FIG. 3 is a block diagram showing a configuration related to position control of a drive target according to the first embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration related to position control of a drive target according to the second embodiment of the present invention.

FIG. 5 is a block diagram related to position control of a drive target according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a structure of an intermediate transfer belt which is a driving target.

FIG. 7 is a Bode diagram from a motor torque to be driven to a belt surface position.

FIG. 8 is an open loop transfer characteristic diagram from a drive shaft target angle to a drive shaft angle including a controller.

FIG. 9 is an open loop transfer characteristic diagram from a target position to a surface position of a driven object including a controller of an inner feedback loop.

FIG. 10 is a block diagram relating to position control of a drive target according to the fourth embodiment.

FIG. 11 is a diagram showing a comparison of position deviations with and without the arrangement of a disturbance estimation observer.

FIG. 12 is a block diagram relating to position control of a drive target according to the fourth embodiment.

FIG. 13 is a diagram showing a comparison of drive shaft speeds at the start of movement of the intermediate transfer belt with and without the arrangement of a feedforward system.

FIG. 14 is a diagram showing a result at the time of belt slip when the transfer characteristic shown in FIG. 9 (a configuration for performing feedback of the drive shaft and feedback control for the belt surface position of the intermediate transfer belt).

FIG. 15 is a block diagram showing a signal interpolation circuit according to a sixth embodiment of the present invention.

FIG. 16 is a schematic configuration diagram of an image forming unit of a color copy or color printer including an intermediate transfer belt.

FIG. 17 is a diagram illustrating a configuration example of a tandem image forming apparatus.

FIG. 18 is a plan view showing a conventional belt conveyance device.

[Explanation of symbols]

101 intermediate transfer belt 102 drive shaft 103 drive shaft timing pulley 104 timing belt 106 belt drive motor 107 encoder scale 108 optical head 109 drive shaft encoder 110 (110a to 110d) photoconductor 111 drive shaft 112 timing belt 113 drum drive motor 114 rotary Encoder 115 Paper transfer roller 116 Laser head 201 Microcomputer 202 Microprocessor (CPU) 203 Read only memory (ROM) 204 Random access memory (RAM) 205, 207 State detection interface (I /
F) 206 bus 208 driving I / F 209 driver 210 driving I / F 211 driver 301 comparing means 302 surface position controlling means 303 adding means 304 comparing means 305 position controlling means 401 comparing means 402 surface position controlling means 403 adding means 404 Comparison means 405 Position control means 501 Comparison means 502 Surface position control means 601, 602 Teeth 603 Image forming unit 604 Belt detent 605 Driven shaft 606 Teeth 1001 PI controller 1002 Disturbance estimation observer 1201 Feedforward system 1501 Signal interpolation circuit 1502 Pattern signal Counter 1503 Clock counter 1504 Image signal generating unit 1600 Image forming unit 1601 Charging charger 1602 Photoconductor cleaning device 1603 Revolver developing unit 1604 Intermediate transfer unit Knit 1605 Secondary transfer belt 1611 Bk developing machine 1612 C developing machine 1613 M developing machine 1614 Y developing machine 1616 Belt cleaning blade 1617 Lubricant application brush 1618 Zinc stearate 1620 Secondary transfer unit 1625 Primary transfer bias roller 1626 Belt tension roller 1627 Secondary transfer counter roller 1628 Cleaning counter roller 1629 Ground roller 1631 Primary transfer power supply 1632, 1633, 1634 Support roller 1635 Secondary transfer power supply 1650 Registration roller pair 1656 Transfer paper charge removal charger 1657 Belt charge removal charger 1658 Cleaning blade 1701 Driven roller

Continued front page    F-term (reference) 2H200 FA04 FA20 GA12 GA23 GA34                       GA44 GA47 GB12 GB13 GB41                       HA02 HA12 HA28 HB03 HB12                       HB22 HB26 JA02 JB06 JB49                       JB50 JC03 JC19 JC20 LA11                       LA12 LA27 LB02 LB12 LB13                       PA11 PA12 PA22 PB14 PB15                       PB39                 2H300 EB08 EB12 EC05 EC12 EC15                       EC16 EF03 EF06 EF08 EH15                       EJ09 EJ15 EK03 GG27 QQ12                       RR18 RR19 RR20 RR50 TT04                       TT05

Claims (25)

[Claims] 1. A belt moving device comprising a drive shaft for moving a belt and a transmission means for transmitting a driving force from a motor to the driving shaft, wherein the belt moving device moves the belt by the driving force from the motor. Marker detection means for detecting a marker provided on the belt for recognizing the position in the moving direction of the drive shaft, a rotation state detection means for detecting the rotation state of the drive shaft, and a detection result of the marker detection means, First, to create correction information for correcting the position of the belt in the moving direction
Correction information creating means, second correction information creating means for creating correction information for correcting the rotation state of the drive shaft based on the detection result of the rotation state detecting means, and the first and second A belt moving device, comprising: a control unit that controls the movement of the motor based on the correction information of the correction information creating unit. 2. The first correction information creating unit sets the maximum response frequency of the correction information to be created smaller than the maximum response frequency of the correction information created by the second correction information creating unit. The belt moving device according to claim 1. 3. A drive shaft is rotated by driving a motor,
In a belt moving device that drives a belt, a detection unit that detects the surface position of the belt, and a position control unit that feeds back the surface position detected by the detection unit and causes the surface position of the driven object to follow a target position. And a belt moving device. 4. A drive shaft is rotated by driving a motor,
In a belt moving device that drives a belt, a rotation state detection unit that detects the rotation state of the motor shaft, and a rotation state detected by the rotation state detection unit are fed back to set the motor shaft target position to the target surface of the belt. A belt moving device, comprising: a control unit that performs a movement control that causes the motor shaft to follow the target position so that the displacement from the position is eliminated. 5. A tooth is formed at at least one position in an axial direction of a drive shaft on which the belt is stretched, a tooth that meshes with a tooth of the drive shaft is formed on the belt, and the belt is rotated by rotation of the drive shaft. The belt moving device according to claim 1, wherein the belt moving device is moved. 6. The driving surface of the drive shaft is provided with a member having a large friction coefficient, and the belt is moved by rotation of the drive shaft. Belt moving device. 7. The belt moving device according to claim 1, wherein the belt is an intermediate transfer belt and / or a paper transport belt provided in the image forming apparatus. 8. The cross frequency W of the open-loop transfer characteristic from the target drive shaft angle with respect to the drive shaft to the drive shaft angle including the controller.
When the relationship between cd and the natural frequency Wpd from the drive shaft torque to the surface position of the belt is Wcd> Wpd, the target drive shaft angle is controlled so that there is no deviation from the target surface position of the belt. The belt moving device according to claim 1, wherein the belt moving device is a belt moving device. 9. The cross section frequency Wcm of open loop transmission characteristics from a target motor shaft angle with respect to the drive shaft to a motor shaft angle including a mechanical system from the controller to the drive shaft, and the drive shaft torque to the belt. When the relationship of the natural frequency Wpd up to the surface position of is Wcm> Wpd, the target motor shaft angle is controlled so as not to deviate from the target surface position of the belt. The belt moving device described. 10. The cross section frequency Wcs of the open loop transfer characteristic from the target position to the surface position of the belt including the controller, and the natural vibration from the drive shaft torque or the motor shaft torque to the surface position of the belt. When the relationship of several Wpdm is Wpdm> Wcs and stable control is possible, only the surface position of the belt is fed back to perform control so as to eliminate the deviation from the target surface position of the belt. Item 5. The belt moving device according to item 3. 11. The crossing frequency Wcd of an inner feedback loop for feeding back the rotation state of the drive shaft detected by the rotation state detecting means to follow the drive shaft target position, and the inner side from the target position. 2. The control of the outer feedback loop, wherein the relationship of the crossover frequency Wcs of the open-loop transfer characteristic to the surface position of the belt including the controller of the feedback loop is such that Wcd> Wcs is satisfied. 8. The belt moving device according to any one of 8. 12. The crossing frequency Wcm of an inner feedback loop that feeds back the rotation state of the drive shaft detected by the rotation state detection unit to follow the drive shaft target position, and an inner side from the target position. 10. The relationship of the crossover frequency Wcs of the open loop transfer characteristic up to the surface position of the belt including a controller of a feedback loop executes the control of the outer feedback loop with Wcm> Wcs. The belt moving device described in any one. 13. The control means is configured by adding a disturbance estimation observer to a PI controller, and is −20 db / de as a slope of a crossover frequency Wcs of an open loop transfer function from a target position to a surface position of the belt.
2. An integration characteristic of c is provided.
~ The belt moving device according to any one of 4, 10 to 12. 14. The control means, at the start of driving of the belt, multiplies a target position of a ramp function by a function for smoothing the target position, and sets a new target position as a comparison signal of the measurement output, and the target position. 14. A feedforward system circuit for supplying a feedforward current to the motor by multiplying a function for smoothing the above by a reciprocal number of a transfer function of a controlled object, any one of claims 1 to 4, 10 to 13. The belt moving device described in one. 15. The belt moving device according to claim 5, wherein the teeth are formed on a portion of the belt other than the image forming portion. 16. The belt is stretched between the drive shaft and a plurality of rollers, and at least a roller in the transfer nip portion of the plurality of rollers has an axial length that does not contact the teeth of the belt. The belt moving device according to claim 5, wherein the belt moving device is a belt moving device. 17. The belt moving device according to claim 1, wherein the transmission means from the motor to the drive shaft is composed of a timing belt and a timing pulley. 18. The transmission means from the motor to the drive shaft is formed of a gear.
16. The belt moving device according to any one of 16. 19. The transmission means from the motor shaft to the drive shaft is a direct drive in which the motor shaft and the drive shaft are integrated or the motor shaft and the drive shaft are coupled by a coupling. The belt moving device according to any one of 1 to 16. 20. The control means performs A / D conversion on the marker composed of the slit pattern detected by the marker detecting means, and based on the output of the A / D conversion, the distance between the slit patterns indicated by the detected marker. 20. The belt moving device according to claim 1, further comprising a signal interpolating unit that interpolates a position. 21. The signal interpolation means, wherein the control means temporally interpolates between the pulse edges of the signal pulse of the marker having the slit pattern detected by the marker detection means with a constant interval clock having a shorter period than the signal pulse. 21. The belt moving device according to claim 1, further comprising means. 22. The belt movement according to claim 1, wherein the control means drives and controls the belt by using a single DSP or a single microcomputer. apparatus. 23. The control means gives an operation result discretized at a sampling time of a control operation as an input to the motor for the servo drive operation using the DSP or the microcomputer. Item 23. The belt moving device according to item 22. 24. The eccentricity correction encoder which is provided coaxially with the drive shaft or the shaft of the motor, wherein the rotation state detecting means is an encoder.
23. The belt moving device according to claim 23. 25. An image forming apparatus comprising the belt moving device according to claim 1, wherein the image forming apparatus is provided as an intermediate transfer belt for forming the belt image. An image forming apparatus comprising: an image forming unit that forms a color image of a plurality of colors on a transfer paper by movement control.